In recent years, portable information terminals typified by smartphones have been actively developed. Portable information terminals, which are a kind of electronic devices, are desired to be lightweight and compact for users. Wearable terminals that are used while being worn on users have also been developed.
Devices such as wearable devices and portable information terminals include secondary batteries that are capable of being repeatedly charged and discharged, in many cases. Such devices are required to be lightweight and compact and thus there is a problem in that the capacities of secondary batteries used therein are inevitably low, limiting the operation time of the devices. Secondary batteries used in such devices should be lightweight and compact and should be capable of being used for a long time.
Patent Document 1 discloses a highly flexible battery using a thin, pliant film-like material as an exterior body.